May 11 Event Will Mark 90th Anniversary for GPS

On May 11, Caltech's Division of Geological and Planetary Sciences (GPS) will celebrate its 90th anniversary with a daylong symposium and celebration featuring speakers who contributed to the division throughout its history as well as lab tours and posters about current research.

Speakers will include alumni from the 1930s to the present—among them centenarians Mel Levet (BS '39, MS '40) and Walter Munk (BS '39, MS '40). Levet is a geologist (who also pitched for and coached the Beavers baseball team in the 1930s) and Munk is a physical oceanographer who is renowned for his work on ocean circulation and tides. Throughout the day, tours will be conducted of three facilities: the media center of the Caltech Seismological Laboratory, more colloquially called the Seismo Lab, an internationally recognized earthquake research facility; the Earth Surface Dynamics Laboratory (or "Flume Lab"), a tilting flume used to study erosion and debris flows; and the Bruce Murray Laboratory for Planetary Visualization, a state-of-the-art image processing and data visualization lab. The tours will offer alumni and friends a firsthand look at the division's ongoing research. The following day, a 195-mile round-trip, nine-hour excursion has been scheduled to explore the San Andreas Fault. The bus tour will include stops at the Cajon Pass, Lost Lake, Devil's Punchbowl Natural Area, and several other locations.

"Caltech excels at reinventing itself to create new research directions while also strengthening strong programs at the core of Earth and planetary science. Our students, alumni and faculty across many generations have collaborated to establish these outstanding programs. This event is a celebration of those collaborations and the accomplishments and distinguished careers of our alumni and current students," says John Grotzinger, the Ted and Ginger Jenkins Leadership Chair of GPS and the Fletcher Jones Professor of Geology.

GPS began as the Department of Geology in 1926. The department originally partnered with the then-independent Seismological Laboratory, which was established in 1921 in the hills above Pasadena and managed jointly by Caltech and the Carnegie Institution of Washington until Caltech took full charge of its administration in 1937. (The Seismo Lab finally moved onto Caltech's campus in 1974 with the construction of the Seeley G. Mudd Building of Geophysics and Planetary Sciences, also known as South Mudd.) Since the 1920s, Caltech has collaborated with the United States Geological Survey on the Southern California Seismic Network (SCSN), which monitors ground motion in the region via seismometers at 410 sites and provides timely information about earthquakes to first responders.

The department made significant early advances in earthquake science, including the development of a formula for measuring the magnitude of earthquakes—the Richter Scale—by Caltech's Charles Richter (PhD '28) and Beno Gutenberg, the Seismo Lab's founding director, in 1935. (The Richter Scale was replaced in 1977 with the invention of the Moment Magnitude Scale by Caltech's Hiroo Kanamori, the John E. and Hazel S. Smits Professor of Geophysics, Emeritus.) More recently, earthquake scientists at GPS have collaborated with researchers in the Division of Engineering and Applied Science to roll out a network of low-cost, easy-to-install seismometers. The goal of the project, known as the Community Seismic Network, is to collect highly granular and detailed information about how tremors shake the Los Angeles area and how different buildings respond to those quakes. Such information would be crucial to first responders in the aftermath of a major earthquake, directing them to the hardest-hit areas.

Another early focus of research for GPS was paleontology. Indeed, paleontologist Chester Stock served as division chair from 1947-50, and also as chief science curator at the Los Angeles County Museum of History, Science, and Art (now the Natural History Museum of Los Angeles County) for several years. The museum still retains a collection of specimens from Stock, who excavated dinosaur and mammal fossils throughout the American West and northern Mexico.

As the United States entered the space race in the 1950s, the division shifted away from paleontology and toward geochemistry and planetary science. Led by chair Robert Sharp (BS '34, MS '35, and namesake of Mars's Mount Sharp, the base of which served as the landing site for the Mars Curiosity rover in 2012), the division changed its name to Geological and Planetary Sciences in 1960 and forged a partnership with the Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA. The division worked with JPL to develop tools and techniques for studying the solar system. Among other advances, Clair Patterson, professor of geochemistry, determined the age of the earth as 4.55 billion years, while Gerald Wasserburg, John D. MacArthur Professor of Geology and Geophysics, built a mass spectrometer for making high-precision measurements of lunar samples obtained by the Apollo missions.

The division's rich planetary science tradition has been carried on by its current leadership in NASA's exploration of Mars. Grotzinger served as project scientist for the Mars Science Laboratory Curiosity rover mission from 2007 to 2015, and Kenneth A. Farley, the W. M. Keck Foundation Professor of Geochemistry, is project scientist on the upcoming Mars 2020 mission. Caltech planetary scientists are also reshaping our understanding of the solar system itself. In 2005, GPS's Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, made headlines with the discovery of the dwarf planet Eris, which ultimately led to Pluto being downgraded from a planet to a dwarf planet. In 2016, he and colleague Konstantin Batygin, assistant professor of planetary science, followed up that discovery with the announcement that an actual (but as-yet unobserved) ninth planet exists, touching off a worldwide race among astronomers to locate the planet.

In recent years, the division has expanded its program in environmental science with key hires in the field of climate science. It also established the Ronald and Maxine Linde Center for Global Environmental Science in 2008. The center, with an $18 million endowment from Ronald Linde (MS '62, PhD '64) and his wife, Maxine, is working to develop solutions to environmental issues like air pollution and climate change. The division has also established a nation-leading program in geobiology, the study of the interface between the biosphere and the earth. This new field explores how the earth's history has shaped life and how life has shaped the earth's history. In September, Caltech geobiologists Dianne Newman and Victoria Orphan earned national recognition when both were awarded MacArthur Fellowships.

"Some of the most difficult problems of our time relate to interactions within the Earth system and other planetary systems," Grotzinger says. "In the future, GPS will be well positioned to participate in elucidating the fundamental physics of earthquakes and how this enables their prediction; the processes that regulate climate and how this impacts local and global change; and address the inevitable questions of where do we come from and are we alone."

Members of the Caltech community interested in attending the GPS 90th anniversary celebration are asked to register for the event online.